The waist of the pants is doll's waist plus 1" for seam allowances and 1-2 inches for ease of movement and getting them on.
Crotch seam needs to match measurement plus 1" for seam allowances and some for ease of movement. Crotch seam needs to have a nice curve to it. I made front and back the same.
Sew inside leg seams together. Leave one wrong side out-turn the other.
Put right side inside of wrong side and sew crotch seam.
When finished, it looks like this. Now ready for elastic.
Measure elastic on doll's waist to see how long it needs to be, adding about 1/2" for s.a.
Since I was having a lazy day, I just sewed the elastic with a zigzag straight to the pants. EASY!!! That is also the method I use for my skirts I've been making. I love it.